1. The Field of the Invention
The invention generally relates to the filed of component testing. More specifically, the invention relates to current protection used in test apparatuses for component testing.
2. Description of the Related Art
Manufacturing is an essential industry to provide products for all aspects of life. Manufacturing produces everything from large machinery to microscopic components such as those found in semiconductor chips. A part of the manufacturing process is quality control. Quality control helps to assure that manufactured components meet the expectations of consumers and the standards that a manufacturing facility sets for itself. High standards that translate to high quality components can set one manufacturer apart from other manufacturers. Quality control can include several components including inspection and testing.
Testing may include several components, including functional testing and burn in testing. Functional testing tests components to make sure that they perform within acceptable limits. Additionally, and especially in testing of devices like electrical devices, functional testing may be done to determine a device's ratings. Illustratively, one type of electrical device is the semiconductor laser. A semiconductor laser functions by producing coherent light in response to a current passed through the laser. Functional testing may be performed to determine how much current is needed for the laser to begin producing coherent light. Further, functional testing may also be used to determine how much coherent light is produced as a function of the current that is passed through the semiconductor laser. The semiconductor laser fails functional testing if it does not produce light or does not produce light at a sufficiently low current. Even if the semiconductor laser produces light at a sufficiently low current, the semiconductor laser has specific characteristics. Semiconductor lasers can be sorted into categories depending on their specific characteristics, which are discovered through functional testing.
Burn in testing tests devices for a period of time to make sure that the devices are not prone to failure. For example, a device may be connected to a power source and operated for a period of time. After the device has operated satisfactorily for a sufficient period of time, one can be reasonably assured that the device will not fail prematurely when finally installed in an end product.
Often, a device will contain flaws such that when connected for testing, the device causes a “short circuit” to the power source being used to test the device. In the example described above with a semiconductor laser, this may occur because of impurities in the semiconductor laser epitaxial structure or due to metal that has not been properly etched or for other reasons. These short circuits can causes fuses to blow or breakers to trip in the power source or in a source supplying the power source. Blown fuses and tripped breakers will halt testing at a test station until the fuse has been changed or the breaker reset. This clearly can cause inefficiencies in the testing process and can result in delays and increased costs.